The automatic tuning arrangement of the invention has especial application to an oscillator circuit arrangement for supplying dc modulated pulses of a predetermined frequency (i.e. capacitor charging pulses and a variable number of timing pulses) through an inductive coupling arrangement to a chaff-dispensing rocket located ready for launch within the barrel of a rocket launcher. Such inductive coupling arrangements and rocket control circuitry are described in our co-pending British Patent Application No. 8401893. Due to various factors, such as environmental conditions, manufacturing tolerances etc, the reactance of such inductive coupling arrangements can vary and thereby produce a change in the resonant frequency of the inductive coupling arrangement.
In order to transmit the requisite electrical power to the rocket through the capacitor charging pulse, it is necessary to ensure that the frequency of the charge pulse derived from the oscillator circuit arrangement equals the resonant frequency of the inductive coupling arrangement otherwise rocket failure due to failure of the rocket to ignite or to dispense chaff as required may result.